A healthy, patent urethra is important for the maintenance of a good quality of life. Approximately 200 million people worldwide suffer from urethral disease. Patients who present with congenital or acquired abnormalities may require surgical reconstruction with non-urethral tissues, and complications may ensue. The overall goal of this project is to eventually improve the treatment of urethral diseases with the use of tubularized bioengineered autologous urethral tissues. The series of experiments designed in this application are the definitive studies required toward the goal of making the technology of bioengineered urethras available to patients requiring tubularized replacements. The specific aims of this project are: Specific Aim 1: To determine the feasibility of engineering medium sized tubularized segments of small caliber urethras. We will test the following hypotheses: (1) that medium sized tubularized segments of small caliber urethras can be engineered; (2) that the engineered tubularized urethras will remain functional over time; and (3) that the engineered urethras will not stricture over time. Specific Aim 2: To determine the feasibility of engineering long tubularized segments of large caliber urethras. We will test the following hypotheses: (1) that bioengineered urethral tissues can be used to replace long tubularized segments of large caliber urethras; (2) that the engineered urethras will remain functional over time; and (3) that the engineered urethras will not stricture over time. Specific Aim 3: To determine the short term and long term phenotypic and functional characteristics of tubularized urethral tissues engineered for subtotal replacement. We will test the following hypotheses: (1) that the phenotypic and functional parameters of the medium length, small caliber tubularized engineered tissues used for subtotal urethral replacement become adequate over time; (2) that the phenotypic and functional parameters of the medium length, small caliber tubularized matrices without cells used for subtotal urethral replacement are inadequate; (3) that the phenotypic and functional parameters of the long tubularized, large caliber engineered urethral segments used for subtotal replacement become adequate over time; and (4) that the phenotypic and functional parameters of the long tubularized, large caliber matrices without cells used for subtotal replacement are inadequate.